The present invention is directed to an apparatus and method for improving the formation of multiple lateral wells in a new wellbore and positive, selective reentry of each lateral well.
Several advantages are provided by drilling relatively high angle, deviated or lateral wells from a generally common wellbore such as a) access to the regular oil and gas reserves without additional wells being drilled from the surface, b) avoiding unwanted formation fluids, c) penetration of natural vertical fractures, and d) improved production from various types of formations or oil and gas reserves. Additionally, reentry of one or more lateral wells is often required to perform completion work, additional drilling, or remedial and stimulation work. Thus, lateral wells have become commonplace from the standpoint of new drilling operations and reworking existing wellbores.
Ordinarily, lateral well completion and/or reentry requires expensive downhole wireline surveys to accurately position the diverter or whipstock which is used to direct the boring or completion tool through a wall of a generally vertical wellbore into the adjacent formation. Without a survey, the lateral well formed may not be accurately recorded for purposes of reentry. For example, U.S. Pat. Nos. 4,304,299; 4,807,704; and 5,704,437 each describe a method and/or apparatus for producing lateral wells from a generally vertical common wellbore using conventional techniques and tools. In each instance, one or more lateral wells may be produced at a different depth and location in the common wellbore and reentered. Consequently, the whipstock must be repositioned at the new depth and location. Each time the whipstock is repositioned at a different depth and location, the change in depth and lateral orientation relative to a point of reference is recorded. In many applications using conventional threaded connections, the exact depth and location of each lateral well formed cannot be accurately or efficiently recreated using the same system and technique. As a result, a downhole directional survey is necessary to relocate the exact depth and location of each lateral well upon reentry.
Recognizing the disadvantages of the foregoing techniques, U.S. Pat. No. 2,839,270 and, more recently, U.S. Pat. No. 5,735,350 address the need for a more accurate method and/or apparatus for producing and reentering lateral wells without the need for a directional survey. For example, U.S. Pat. No. 2,839,270 describes a technique for selectively forming a lateral well through a wall of a common wellbore at a predetermined depth and lateral orientation by means of a supporting apparatus which includes apertures formed at predetermined locations in the supporting apparatus. The apertures determine the relative depth and lateral orientation of each lateral well and are prefabricated according to the particular common wellbore in which the supporting apparatus is installed. The whipstock is then positioned using one or more specially designed latches which engage a corresponding aperture designed for receipt of the respective latch.
Similarly, U.S. Pat. No. 5,735,350 describes a method and system for creating lateral wells at pre-selected positions in a common wellbore by means of a diverter assembly having a plurality of locator keys specially designed to engage a corresponding nipple formed in the wellbore casing having a unique profile. Although this technique may be employed in new and existing wells, it is expensive and, in some instances, inappropriate because the prefabricated keys and nipples are permanently and integrally formed according to the particular formation characteristics of the common wellbore in which the system is installed.
More recently, a system and method for use in a completed wellbore lined with casing was described in U.S. Pat. No. 6,427,777. This system uses a directional survey to position an anchor at a predetermined depth and lateral orientation relative to a longitudinal position and lateral position of the desired lateral well. Because a directional survey is used to position the anchor after the casing is set and secured, the exact location of a pre-formed opening in the casing is difficult to find. And, because the system is designed for completed wellbores, the system typically requires running equipment in the wellbore which is different than the equipment used to line and secure the wellbore with casing. Finally, the casing must be milled with a different type of bit than the bit used to drill through the formation when the system is used in a completed wellbore without pre-formed openings in the casing. As a result, the system must be run in the wellbore twice to form each lateral well.
It is therefore, an object of the present invention to provide an apparatus and method which can be used to secure the casing in a new wellbore and improve the formation of multiple lateral wells in a cost-efficient manner.
It is another object of the present invention to provide an apparatus and method which improves the formation and reentry of multiple lateral wells without the use of an anchor.
It is another object of the present invention to provide an apparatus and method which improves the accuracy of locating pre-formed openings in the casings.
It is an advantage of the present invention to provide an apparatus and method which reduces the time and cost associated with the formation of multiple lateral wells through the use of pre-formed openings in the casing.
It is an advantage of the present invention to provide an apparatus and method which can be used with conventional and/or standard equipment to secure the casing in a new wellbore and form multiple lateral wells.
It is another advantage of the present invention to provide an apparatus and method which is easy to install and operate within the wellbore.
In accordance with the foregoing objects and advantages, the present invention includes an apparatus, hereinafter referred to as an orienting sleeve, which is positioned in a wellbore lined with multiple casing segments. The orienting sleeve includes a first end connected to one of the casing segments, a second end, a longitudinal reference point and a lateral reference point.
A portion of the first end forms a seat. The valve is positioned in the second end of the orienting sleeve and permits movement of a fluid from the first end of the orienting sleeve to a second end of the orienting sleeve and restricts movement of the fluid from the second end of the orienting sleeve to the first end of the orienting sleeve. In order to improve the performance of the valve, the second end is connected to a float shoe which has another valve for permitting movement of the fluid from the first end of the orienting sleeve through the float shoe and restricting movement of the fluid from the wellbore through the float shoe. Alternatively, the second end of the orienting sleeve may be connected to a first end of another one of the casing segments which forms a reservoir for receipt of a portion of the fluid. A second end of the casing segment is connected to a float shoe having another valve for permitting movement of the fluid from the first end of the orienting sleeve through the float shoe and restricting movement of the fluid from the wellbore through the float shoe. As another alternative, the second end of the orienting sleeve includes another valve for permitting movement of the fluid from the first end of the orienting sleeve through the second end of the orienting sleeve and restricting movement of the fluid from the second end of the orienting sleeve to the first end of the orienting sleeve. Each valve utilized in the orienting sleeve or the float shoe is a plunger valve, however, may include any other type of valve capable of performing the function thus described.
A sealing member having a fluid passage therethrough is used to transfer the fluid from a surface above the wellbore through the orienting sleeve to a space between the casing segments and the wellbore. The fluid secures the casing segments to the wellbore. The orienting sleeve includes a seal to restrict the fluid from passing between the orienting sleeve and the scaling member.
The longitudinal reference point enables the location of a longitudinal position on at least one of the casing segments and the lateral reference point enables the location of a lateral position on the at least one of the casing segments. The lateral position and the longitudinal position define either an opening in at least one of the casing segments which is covered by a substantially impermeable material, or a desired region of interest in the formation adjacent to the lateral position and longitudinal position.
An orienting member and the orienting sleeve are used to effectively locate the lateral position and the longitudinal position of the opening in at least one of the casing segments. The sealing member and orienting member each include a shoulder which engages the seat on the orienting sleeve when the sealing member or orienting member is engaged with the orienting sleeve.
At least one of the sealing member and the orienting member includes a flange. The first end of the orienting sleeve includes a channel with an opening in the seat for receipt of the flange when the sealing member or the orienting member is aligned with the orienting sleeve. The channel extends toward the second end of the orienting sleeve. The flange substantially prevents rotational movement of the orienting member or the sealing member when the flange is disposed substantially within the channel.
The orienting sleeve includes a guide having a passage therethrough for receipt of a lower portion of the sealing member or the orienting member. The sealing member and the orienting member each include a reciprocating guide for alignment with the orienting sleeve when the guide and reciprocating guide are substantially engaged. In another embodiment, the orienting sleeve includes a key instead of a guide. Each of the respective sealing member and orienting member include a guide with a keyway for alignment with the orienting sleeve when the key enters the keyway. In either embodiment, the channel or the key defines the lateral reference point, and a portion of the orienting sleeve between the first end and the second end defines the longitudinal reference point. Preferably, the first end or the second end is chosen as the longitudinal reference point.
Thus, the sealing member and orienting sleeve are used to transfer the fluid, preferably cement, which secures the casing to the new wellbore. And, the orienting member and orienting sleeve are used to effectively form multiple lateral wells through the casing or pre-formed openings in the casing.
The present invention also includes a method to secure multiple casing segments within a new wellbore and improve the formation of multiple lateral wells through one or more of the casing segments, or one or more pre-formed openings in the casing segments, using the orienting sleeve, orienting member and sealing member thus described.
The method comprises the steps of: a) connecting the first end of the orienting sleeve to one end of a plurality of casing segments and connecting the second end of the orienting sleeve to a float shoe, b) lowering the casing segments, orienting sleeve and float shoe into the new wellbore until the orienting sleeve reaches a predetermined depth and lateral orientation, c) lowering the sealing member on a drill string until the sealing member is substantially engaged within the orienting sleeve, d) transferring a fluid through the drill string and sealing member from a surface above the wellbore to a space between the casing segments and the wellbore in order to secure the casing segments to the wellbore, e) removing the drill string and sealing member from the wellbore, f) lowering the orienting member on a drill string until the orienting member is substantially engaged within the orienting sleeve
Once the orienting member is substantially engaged within the orienting sleeve, the process of forming a lateral well may be performed using the connections and related components described in reference to U.S. Pat. No. 6,427,777, incorporated herein by reference. By replacing the anchor with the orienting sleeve, the lateral reference point and longitudinal reference point may be used to accurately locate a pre-formed opening in the casing for each respective lateral well. As a result, the process of forming a lateral well through the casing is reduced to a single step and the need to mill through the casing is eliminated. Alternatively, however, the lateral reference point and longitudinal reference point may be used to accurately locate the lateral position and longitudinal position of each respective lateral well.
Although the terms longitudinal and lateral are used herein for convenience, those skilled in the art will recognize that the apparatus and method of the present invention may be employed with respect to wells which extend in directions other than generally vertically or horizontally.
The foregoing has outlined rather broadly the objects and advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional objects and advantages of the invention, which form the subject of the claims of the invention, will be described below. Those skilled in the art should appreciate that they may readily use the concept and specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.